Originally posted by: AndyHam

Dear IBM,

I have one set of interval variables: some of them must be present and some of them are optional.
How can I model the mix? Is there syntax something like below?

      dvar interval itvJobs[j in JobList]  (j.type=="Return" --> Optional)  (j.type=="Pkup" --> Present);

Best Regards,

Andy

Originally posted by: PhilippeLaborie

Hi Andy,

Yes there is a syntax for that, you can write:

dvar interval itvJobs[j in JobList]  optional(j.type=="Return");

Originally posted by: PhilippeLaborie

I forgot to add that another way to do that is just to define all interval variables optional and post 'presenceOf' constraints on the present ones:

dvar interval itvJobs[j in JobList]  optional;
...
subject to {
  forall(j in JobList: j.type=="Pkup") {
    presenceOf(itvJobs[j]);
  }
};

Originally posted by: AndyHam

Big thanks!
Also, controlling the presence status inside "Subject to" gives me more flexibility.
I tested it. It worked beautifully.
There seems to be always WAY in CP ^^
Have a great day!